Dyeing natural polyamide fibers

ABSTRACT

Dyeing wool brilliant pastel shades with dyes which are absorbed from an acid medium at low temperature in the presence of hydrogen peroxide or performic acid.

Umted States Patent 1191 1111 3,912,447

Schmidt Oct. 14, 1975 [54] DYEING NATURAL POLYAIVHDE FIBERS FOREIGN PATENTS OR APPLICATIONS [75] Inventor: Oswald Schmidt, Baden-Baden, 1,032,260 6/1966 United Kingdom Germany 254,1 19 5/1967 Austria [73] Assignee: BASF Aktiengesellschaft, gzlzg j Ludwigshafen (Rhine), Germany Germany pp Fell, Melliand Textilberichte, 1966, 1, 64-66.

'[30] Foreign Application Priority Data imary Examinr.10Seph L: schofer Mar. 7, 1973 Germany 2311130 Clmgman Attorney, Agent, or FzrmJohnston, Ke11, Thompson 52 us. c1. 8/19; 8/17; 8/39; & shurfleff [51] Int. Cl.'..... D061 3/16; D06? 1/06; DO6P 3/06 [57] ABSTRACT Fleld of Search l7, Dyeing wool brilliant pastel shades dyes are absorbed from an acid medium at low temperature [56] References C'ted in the presence of hydrogen peroxide or performic UNTTED STATES PATENTS acid 3,374,177 3/1968 Schmidt et a1 252/186 3,551,087 12/1970 Schmidt 8/19 9 Clam, N0 Drawmgs DYEING NATURAL POLYAMIDE FIBERS The present invention relates to an improved process for dyeing natural polyamide fibers which makes use of the pad-batch principle.

Wool and other natural polyamide fibers are dyed as a rule with acid dyes devoid of metal or with a metal complex dye at the boiling temperature in an acid medium, the dyeing period usually being 1 hour. Pale hues, too, are usually dyed at 100C and at least at 80C although the amount of dye to be fixed onto the fiber is fairly small.

In the case of pale brilliant hues use is mainly made of metal-free acid dyes and reactive dyes, while metal complex dyes are less used. Until recently natural polyamide fibers had to be subjected to bleaching prior to dyeing in pastel shades in order to achieve the necessary brillance. Recently such hues have been prepared in a single operation by bleaching direct in the acid dye itself. Oxidizing bleaching in the dye liquor in particular is very effective. This single stage bleaching and dyeing may be carried out by an exhaustion method (long liquor) or by the pad-steam method. Hitherto it has always been thought that high temperatures are necessary for fixing.

it is also known that wool dyeings can be prepared with reactive dyes at ambient temperature if the wool is specially sensitized (by oxidation or reduction) and is then dyed in an alkaline medium (E.T. Fell: Stevenson-Verfahren zur kontinuierlichen Kammzugveredlung, Melliand 47 (1966), 64).

There has been a long-felt desire to dye natural polyamide fibers with dyes which are absorbed from an acid medium while using the lowest possible temperatures; previous attempts in this direction have shown however that at temperatures below 50C there is unsatisfactory fixation of the dye with consequent extensive loss of dye and moreover the dyeings lack brilliance.

I have now found that the said disadvantages can surprisingly be avoided and that good fixation of the dye and high brilliance of the dyeings is achieved in the dyeing of natural polyamide fibers in pastel shades with dyes which are absorbed from an acid medium even at low temperature by making use of the pad-batch principle with a dye liquor which at the time when impregnation takes place contains up to 7 percent by weight (based on the fibers to be dyed) of hydrogen peroxide or the equivalent amount of performic acid.

The process of the invention makes use of the padbatch principle, i.e., the dye liquor is introduced into the fibrous material to be dyed at low temperature and provision is made either for maintaining a short ratio of goods to liquor of the order of about 1:1, for example from 1:07 to 1:13 or when using a larger amount of liquor then reducing to a wet pickup of about 100 percent, for example from 70 percent to 130 percent, and then the fibrous material thus impregnated is left for a long time at low temperature. The impregnation may be carried out for example with a padding machine or by dipping or spraying followed if necessary by squeezing, centrifuging or blowing off the excess liquor. By low temperature we mean a temperature below 50C down to C and preferably of from to 35C; generally it is most convenient to use the prevailing ambient temperature. The fibrous material is allowed to remain until the dye is fixed, i.e., until the fastness properties, particularly wet fastness and light fastness, are not appreciably improved by leaving it any longer. Dwell times of from 10 to 24 hours and preferably from 12 to 18 hours are suitable for the process according to the invention at temperatures of about 20C. The most favorable dwell period can easily by ascertained by a preliminary experiment. It is generally recommendable for the dwell phase to be in off-duty night hours.

The process of the invention may in principle be carried out with all dyes which are absorbed onto natural polyamide fibers from an acid medium. [t has proved to be particularly advantageous in association with acid dyes devoid of metalQThis group includes the acid azo dyes and the acid anthraquinone dyes. in principle 1:1 metal complex dyes and 1:2 metal complex dyes may be used in the process of the invention provided there are not added to the dye liquors stabilizers which form complexes which deprive these dyes of their central atom and thus may cause damage, but they are less suitable than metal-free dyes because of their low brilliance.

One dye or more than one dye is used in the dye 1iquor in an amount such as is conventionally used in padding liquors to achieve pastel shades, i.e., from about 0.1 to 20 grams per liter.

It is essential for the success of the process of the invention that the padding liquor should contain hydrogen peroxide or performic acid. This group of substances is referred to hereinafter also as peroxidic agents.

Hydrogen peroxide may be added to the padding liquor in the form ofa solution of any strength. It is preferable to use the commercial about to percent solutions. It may however also be used in the form of an adduct of urea and hydrogen peroxide. Performic acid may be prepared for example as described in British Pat. No. 1,010,425. it is particularly advantageous however to use solutions of performic acid which have been prepared as described in U.S. Pat. No. 3,374,177 which is incorporated herein by reference, and it has proved to be very suitable to use the stabilizers for active oxygen described in that Patent. The amount of stabilizer which can be used is within the conventional range for such substances; it is usually from about 15 to 30 percent by weight of the peroxidic agent used, calculated as hydrogen peroxide. Another very advantageous possibility for carrying out the process of the invention is the use of hydrogen peroxide and performic acid solutions having a composition as described in British Pat. No. 1,184,940 which is incorporated herein by reference, i.e., which contain inter alia certain amounts of aliphatic, aromatic or cycloaliphatic dicarboxylic acid of up to ten carbon atoms.

The padding liquor of the invention contains hydrogen peroxide and/or performic acid in an amount equivalent at the time of padding to up to 7 percent by weight of hydrogen peroxide based on the fibers to be dyed. The concentration of the said substances at which this limiting value is reached depends on the ratio of goods to liquor used. The maximum concentration of hydrogen peroxide in the liquor is g/l for a goods to liquor ratio of 1:1. Suitable general amounts of peroxidic agent are from 0.15 to 7 percent by weight and preferably from 0.25 to 4 percent by weight calculated as hydrogen peroxide. When a particularly active peroxidic agent (for example many of the preparations described in U.S. Pat. No. 3,374,177 and particularly in British Pat. No. 1,184,940) is used, smaller amounts can often be used without impairing the success of the process of the invention. Thus amounts of these more active preparations of the order of about 60 percent of those specified above, i.e., amounts of up to about 4 percent by weight based on the fibers to be dyed and calculated as hydrogen peroxide have proved to be suitable.

In addition to the said components the padding liquors contain constituents conventionally used in such liquors, especially impregnating auxiliaries and possibly thickening agents. By their wetting and dispersing effect the impregnating auxiliaries provide for rapid and uniform penetration of the goods and for fine dispersion of the dye. Examples of suitable auxiliaries are alkylphenol polyglycol ethers such as octylphenol or nonylphenol heptaglycol or octaglycol ethers, alkylphenol polyglycol ether sulfates such as nonylphenol diglycol ether sulfate, fatty alcohol polyglycol ethers and their sulfates, such as the adduct of two moles of propylene oxide and five moles of ethylene oxide to 1 mole of nonanol, alkylaryl sulfonates such as triethanolamine dodecylbenzenesulfonate, and fatty acid alkanolamides such as coconut oil fatty acid diethanolamine. The padding auxiliaries used are generally well balanced mixtures of such nonionic and anionactive components to which derivatives of phenylglycol such as p-chlorophenylglycol may be added to improve their effectiveness.

The disperson of the dye in the liquor may if necessary be improved further by adding a suitable solvent, as for example chlorinated benzene, phenol or benzyl alcohol. The pH of the padding liquor is adjusted in the same way as is necessary in dyeing from a long liquor for the dye used.

Remarks made about the padding method are applicable analogously to other impregnation methods which may be used instead of padding.

The process of the invention results in such a surprisingly great improvement in dye fixation that it is only now possible to turn the impregnation-dwell principle to good account in dyeing fibers of natural polyamides. The process may be used for any fibers of this type, for example silk and animal hair. The process has its greatest importance for dyeing wool. The material to be dyed may be in the form of fibers, filaments, threads, flock or yarns and preferably as tops, woven cloth, knitted goods or non-woven fabric.

The following Examples illustrate the invention.

EXAMPLES Padding liquors of the following composition are used in the following Examples:

Series A:

none

Series B:

35 g/l of hydrogen peroxide (calculated 100 percent) Series C:

35 g/l of hydrogen peroxide (calculated 100 percent) and 5.5 g/l of Na P O Series D:

35 g/l of hydrogen peroxide (calculated 100 percent); 7 g/l of sodium tripolyphosphate; 2.5 g/l of sodium fumarate; 1 1 g/l of sodium hydroxymethanesulfonate; 5 g/l of hexamethylene tetramine; and 2 g/l of nonylphenol decaglycol ether.

The mixture for series D is as described in British Pat. No. 1,184,940 (cf. Example 7). Performic acid forms in the padding liquor from the mixture.

Wet pickup 100 percent (liquor ratio 1:1). Dwell time: 18 hours at room temperature.

After padding the woollen piece goods are wound on a shaft and the wound package is wrapped in plastics sheeting to prevent evaporation during the dwell period of 18 hours. The package is rotated slowly during the dwell period.

To determine how much of the dye used has not been fixed on the goods during the dwell period, pieces of woollen cloth having a dry weight of 10 g are rinsed for thirty minutes in 500 ml of distilled water at 50C after padding and dwell and from time to time they are squeezed out above the surface of the water. The amount of dye which has passed into the rinsing water is measured colorimetrically and calculated as a percentage of the amount of dye used (0.005 g). The results obtained in the case of the various dyes are given in the following Table and clearly shown the hitherto unknown favorable effect of the peroxidic agents on the fixation of dye at low temperatures.

The values given in columns A to D are percentages by weight of unfixed dye after the dwell period.

Dye (0.05% 0.5 g/l) pH A B C D 1. C.1.Acid Red 151 (26900) 5.0 16.5 3.3 2.2 1.7 2. azo dye from 4,4'-diaminostilbene-2,2'-disulfonic acid 5.0 7.7 0.5 0.5 0.5 m-cresol 3. C1. Acid Red 107 (18025) 2.0 17.2 8.1 4.2 0.5 4. C1. Acid Red (68215) 2.0 33.2 20.8 2.9 1.6 5. C1. Acid Violet 36 (62010) 2.0 21.7 13.5 8.7 1.9 6. C1 Acid Blue 62 (62045) 5.0 38.2 11.2 8.5 8.0 7. C. Acid Red 111 (23266) 5.0 49.3 10.6 8.7 6.8 8. The dye of the formula:

' so n 5.0 13.5 5.0

NH CH I CH-CO-(fH-CH, 1

Br Br CH CH SO H 1 claim:

1. A process for dyeing natural polyamide fibers brilliant pastel shades with dyes which are absorbed from an acid medium by impregnation at a temperature of from to 50C with from 70 to 130 percent by weight based on the fibers to be dyed of a dye liquor which contains from 0.15 to 7 percent by weight, also based on the fibers to be dyed, of hydrogen peroxide or an equivalent amount of performic acid and allowing the impregnated material to dwell at from 0 to 50C while preventing drying until the dye has been fixed and then rinsing and drying the same.

2. A process as claimed in claim 1 carried out at a temperature of from 15 to 35C.

3. A process as claimed in claim 1 wherein a metalfree acid dye which is absorbed from an acid medium is used.

10 7. A process as claimed in claim 1 wherein the impregnated dyed material is left at the prevailing ambient temperature of from 0 to 50C.

8. A process as claimed in claim 1 wherein the impregnated dyed material is left at the prevailing temperature of from 15 to 35C.

9. A process as claimed in claim 8 wherein the dwell period is from 10 to 24 hours. 

1. A PROCESS FOR DYEING NATURAL POLYAMIDE FIBERS BRILLIANT PASTEL SHADES WITH DYES WHICH ARE ABSORBED FROM AN ACID MEDIUM BY IMPREGNATION AT A TEMPERATURE OF FROM 0* TO 50*C WITH FROM 70 TO 130 PERCENT BY WEIGHT BASED ON HE FIBRES TO BE DYED OF A DYE LIQUOR WHICH CONTAINS FROM 0,15 TO 7 PERCENT BY WEIGHT, ALSO BASED ON THE FIBERS TO BE DYED OF HYDROGEN PEROXIDE OR AN EQUIVALENT AMOUNT OF PERFORMIC ACID AND ALLOWING THE IMPREGNATED MATERIAL TO DWELL AT FROM 0* TO 50*C WHILE PREVENTING DRYING UNTIL THE DYE HAS BEEN FIXED AND THEN RINSING AND DRYING THE SAME,
 2. A process as claimed in claim 1 carried out at a temperature of from 15* to 35*C.
 3. A process as claimed in claim 1 wherein a metal-free acid dye which is absorbed from an acid medium is used.
 4. A process as claimed in claim 3 wherein an acid azo dye or an acid anthraquinone dye is used as the metal-free acid dye.
 5. A process as claimed in claim 1 wherein from 0.25 to 4 percent by weight, based on the fibers to be dyed, of peroxidic agent, calculated as hydrogen peroxide, is used.
 6. A process as claimed in claim 1 wherein the material dyed is tops or piece goods.
 7. A process as claimed in claim 1 wherein the impregnated dyed material is left at the prevailing ambient temperature of from 0* to 50*C.
 8. A process as claimed in claim 1 wherein the impregnated dyed material is left at the prevailing temperature of from 15* to 35*C.
 9. A process as claimed in claim 8 wherein the dwell period is from 10 to 24 hours. 